H2S peut être un gaz dominant dans les réservoirs pétroliers carbonatés. Cependant, les recherches sur l'influence de H2S sur la composition et la stabilité thermique du pétrole restent limitées. Dans cette thèse, les interactions entre les hydrocarbures et H2S ont été étudiées de 310 à 350°C, à 700 bar, par pyrolyse confinée en tubes d'or scellés. La pyrolyse d'une huile non soufrée en présence de H2S ont permis de mettre en évidence une nouvelle voie de formation des composés organiques soufrés dans les pétroles. Les pyrolyses des mélanges n-octane/H2S et alkylbenzène/H2S ont permis de proposer les différentes réactions radicalaires pour la formation des produits soufrés principaux : les thiophène, thiols, thiacycloalcanes, alkyl-thiophènes dans le premier cas ; les thiols aromatiques, alkyl-benzothiophènes dans le second. Les résultats obtenus dans le mélange n-octane/H2S ont permis d'établir et valider un modèle cinétique détaillé. Ce mécanisme a permis de montrer que la pyrolyse n-octane/H2S se déroule en chaînes longues et que H2S a un effet inhibiteur sur la consommation du n-octane aux températures supérieures à 320°C, mais accélère fortement la réaction aux basses températures. Des extrapolations du modèle aux conditions géologiques (150-200°C, 700 bar) montrent que H2S a un effet important sur la composition chimique et la stabilité thermique des hydrocarbures. Le modèle permet aussi d'explorer la réactivité de H2S aux conditions de récupération assistée d'huiles lourdes soufrées (injection vapeur, pyrolyse) ou aux conditions de stockages en réservoir pétroliers déplétés / H2S can be a dominant gas in carbonate petroleum reservoirs. However, researches on the influence of H2S on the oil stability are limited in literature. In this thesis, interactions between hydrocarbons (oils, model compounds) and H2S were studied by confined pyrolysis in gold cells from 310 to 350°C under 700 bar. Results of pyrolysis of oil (free of sulfur) in presence of H2S lead to highlight a new pathway of formation of organic sulfur compounds in oils. Pyrolysis of binary mixtures n-octane/H2S and alkylbenzène/H2S allowed to propose different radical reactions for the generation of main sulfur products, namely, thiophene, thiols, thiacycloalkanes, alkyl-thiophenes in the first case ; thiol-aromatics, alkyl-benzothiophenes in the second. Results obtained in the mixture n-octane/H2S led to construct and validate a detailed mechanistic model. The mechanism shows that pyrolysis of n-octane/H2S occurs in long chain and H2S has an inhibition effect on the consumption of n-octane at temperatures above of 320°C, but accelerate the reaction rate strongly at low temperatures. Extrapolation of the kinetic model to geological temperatures and pressures (150-200°C, 700 bar) shows that H2S can significantly influence the composition and stability of hydrocarbons. It is also proposed to apply the model to study the reactivity of H2S under conditions of enhanced recovery (steam injection, pyrolysis) or of geological storage in depleted petroleum reservoirs

L'étude de l'oxydation d'hydrocarbures naphténiques (éthyl-cyclohexane, n-butyl-cyclohexane) et aromatiques (éthyl-benzène, n-butyl-benzène, n-hexyl-benzène) a été réalisée en réacteur auto-agité par jets-gazeux (pression de 1 à10 bar, température de500 à1100 K, richesse : 0,25, 1 et 2, temps de passage:2s). Les produits de réaction ont été quantifiés par chromatographie en phase gazeuse et identifiés par couplage avec la spectrométrie de masse. L'influence sur la réactivité et sur la sélectivité de la richesse, de la pression et de la taille de la chaîne alkyle greffée sur le cycle aromatique ou naphténique a été déterminée. La réactivité de l'éthyl-cyclohexane a également été comparée à celle obtenue pour deux autres composés contenant 8 atomes de carbone (le n-octane et le 1-octène). Les résultats expérimentaux pour l'éthyl-cyclohexane et le n-butyl-benzène sont en bon accord avec des prédictions réalisées à l'aide de modèles de la littérature, sauf pour le composé naphténique pour des températures inférieures à 800 K. Un mécanisme cinétique détaillé d'oxydation de l'éthyl-benzène a été développé (1411 réactions ; 205 espèces) et validé à partir des résultats obtenus lors de cette thèse mais également à partir de résultats disponibles dans la littérature. Ce mécanisme constitue la « base aromatique » implémentée dans le nouveau logiciel EXGAS Alkyl-aromatiques développé parallèlement à cette thèse et qui permet la génération automatique de mécanismes cinétiques d'oxydation des composés Alkyl-aromatiques. Une étude des règles génériques de décomposition des espèces primaires dans le mécanisme secondaire de ce logiciel a été réalisée lors de cette thèse / The study of the oxidation of naphthenic (ethyl-cyclohexane,n-butyl-cyclohexane) and aromatic (ethyl-benzene,n-butyl-benzene, n-hexyl-benzene) hydrocarbons was performed in a jet-stirred reactor (pressure from 1 to10 bar, temperature from 500 to 1100 K, equivalenceratio: 0.25, 1 and2, residence time: 2s). Reaction products were quantified by gas chromatography and identified using mass spectrometry. The influence on the reactivity and the product selectivity of the equivalence ratio, the pressure and the size of the side alkyl chain attached tothe aromatic or naphthenic ringwas determined. The reactivity of ethyl-cyclohexane was also compared to that obtained for two other compounds containing 8 carbon atoms (n-octane and1-octene). The experimental results for ethyl-cyclohexane and n-butyl-benzene have been satisfactorily compared with prediction made using detailed kinetic mechanisms from the literature, except for the naphthenic at temperature below 800 K. A detailed kinetic mechanismfor the oxidation of ethyl-benzene has been developed (1411 reactions, 205 species) and validated from experimental results obtained in this studybut also from results available in literature. This mechanism has now becomethe "aromatic base" implemented in the software EXGAS Alkyl-aromaticswhich has been developed together with this PhD work and which allows theautomatic generation of alkyl-aromatics oxidation kinetic mechanisms. A study of the generic rules of decomposition of primary species in the secondary mechanism of this softwarewas conducted in this thesis

Une nouvelle méthodologie de modélisation cinétique des procédés de raffinage traitant les charges lourdes a été développée. Elle modélise, au niveau moléculaire, la composition de la charge et les réactions mises en œuvre dans le procédé.La composition de la charge est modélisée à travers un mélange de molécules dont les propriétés sont proches de celles de la charge. Le mélange de molécules est généré par une méthode de reconstruction moléculaire en deux étapes. Dans la première étape, les molécules sont créées par assemblage de blocs structuraux de manière stochastique. Dans la deuxième étape, les fractions molaires sont ajustées en maximisant un critère d’entropie d’information.Le procédé de raffinage est ensuite simulé en appliquant, réaction par réaction, ses principales transformations sur le mélange de molécules, à l'aide d'un algorithme de Monte Carlo.Cette méthodologie est appliquée à deux cas particuliers : l’hydrotraitement de gazoles et l’hydroconversion de résidus sous vide (RSV). Pour le premier cas, les propriétés globales de l’effluent sont bien prédites, ainsi que certaines propriétés moléculaires qui ne sont pas accessibles dans les modèles traditionnels. Pour l'hydroconversion de RSV, dont la structure moléculaire est nettement plus complexe, la conversion des coupes lourdes est correctement reproduite. Par contre, la prédiction des rendements en coupes légères et de la performance en désulfuration est moins précise. Pour les améliorer, il faut d'une part inclure de nouvelles réactions d'ouverture de cycle et d'autre part mieux représenter la charge en tenant compte des informations moléculaires issues des analyses des coupes de l'effluent. / In the present PhD thesis, a novel methodology for the kinetic modelling of heavy oil refining processes is developed. The methodology models both the feedstock composition and the process reactions at a molecular level. The composition modelling consists of generating a set of molecules whose properties are close to those obtained from the process feedstock analyses. The set of molecules is generated by a two-step molecular reconstruction algorithm. In the first step, an equimolar set of molecules is built by assembling structural blocks in a stochastic manner. In the second step, the mole fractions of the molecules are adjusted by maximizing an information entropy criterion. The refining process is then simulated by applying, step by step, its main reactions to the set of molecules, by a Monte Carlo method. This methodology has been applied to two refining processes: The hydrotreating (HDT) of Light Cycle Oil (LCO) gas oils and the hydroconversion of vacuum residues (VR). For the HDT of LCO gas oils, the overall properties of the effluent are well predicted. The methodology is also able to predict molecular properties of the effluent that are not accessible from traditional kinetic models. For the hydroconversion of VR, which have more complex molecules than LCO gas oils, the conversion of heavy fractions is correctly predicted. However, the results for the composition of lighter fractions and the desulfurization yield are less accurate. To improve them, one must on one hand include new ring opening reactions and on the other hand refine the feedstock representation by using additional molecular information from the analyses of the process effluents.

A esterificação do sec-butanol com ácido acético, submetida à catálise homogênea, apresenta poucos resultados experimentais de cinética reacional e equilíbrio químico disponíveis na literatura. A presente dissertação visa determinar os parâmetros cinéticos e de equilíbrio químico desta reação de esterificação, empregando modelo cinético de 2ª ordem baseado em atividades. Os experimentos cinéticos foram realizados em reator batelada com auxílio da metodologia Karl Fischer para análise do teor de água e determinação do perfil de frações molares ao longo da reação. A principal dificuldade na modelagem desta esterificação consistiu em representar satisfatoriamente as não-idealidades da mistura em fase líquida, em espacial nas reações cuja fração molar inicial de ácido acético foi superior a 50%. Netas condições admitiu-se a ocorrência de dissociação do ácido acético levando ao surgimento de interações iônicas. O modelo empregado para obtenção das atividades, com base em frações molares, foi o NRTL. Este modelo representou bem as interações moleculares em condição de baixa acidez, mas apresentou desvios em condições de acidez e teores de água mais elevados. O estudo também visou o desenvolvimento de modelos de calibração para um método analítico on-line visando determinar o perfil de frações molares ao longo da reação. O método empregado foi a espectroscopia de infravermelho próximo (NIR), em vista à capacidade deste método analítico em determinar quantitativamente frações molares de água, além dos demais compostos envolvidos. Outro fator determinante ao emprego do NIR é a seu crescente uso no meio industrial, e o presente trabalho visou também contribuir para o uso futuro desta técnica de monitoramento no processo industrial. Modelos de calibração multivariável com conjuntos de calibração interna por validação cruzada se mostraram adequados ao sistema estudado. Calibrações externas resultaram em modelos imprecisos, não sendo possível determinar claramente os fatores responsáveis pela imprecisão. / There is a lack of literature data on the reaction kinetics and equilibrium of the homogeneously catalyzed esterification of sec-butanol with acetic acid. This work aims at obtaining the kinetic parameters and chemical equilibrium parameters of this esterification reaction by using a second order kinetic model based on activities. The kinetic experiments were performed in a batch reactor and the Karl Fischer analytical method was used to determine the molar fraction of water along the reaction progress. The main challenge of modeling this reaction was to represent the highly non-ideal mixture in liquid phase, specially for reactions runs starting with acetic acid mole fraction higher than 50%. In these conditions, it was assumed the occurrence of acetic acid dissociation that leads to ionic interactions. The thermodynamic model used to calculate the activities was the NRTL. This model predicted well the molecular interactions on low acidity conditions but presented deviations when molar fractions of acid and water were higher. The present study also aims to develop calibration models for analytical on-line method to obtain molar fraction profiles along the reaction. Near infrared spectroscopy (NIR) was used due to the possibility of quantitatively analyze water mole fraction, besides the mole fractions of the other components. Another important reason to choose NIR was its crescent use in industry, and the present work intended to contribute towards the future use of this on line monitoring technique in industrial applications. Multivariate calibration models using internal set of calibration and cross-validation seems to be suitable for this system. External set of calibration leads to less accurate models, and the causes of this lack of accuracy were not clearly identified.

In the present work, a super water-absorbent poly(acrylic acid) was synthetized by inverse suspension polymerization, using Span60 as the dispersant, toluene as the dispersing organic phase, trimethylolpropane triacrylate as the crosslinking agent, and sodium persulfate as the initiator. The synthesis was conducted in a small-scale glass reactor operated in semi-batch mode. The following reaction conditions were evaluated: effects of initiator concentration, temperature, percentage of multifunctional cross-linker agent and monomer concentration. Also, two important properties were determined, conversion and gel fraction. A kinetic model including a population balance was employed to simulate the process. The proposed model uses the numerical fractionation technique and is capable of predicting the pre-gel and post-gel properties, the effect of the crosslinking agent level on the polymer properties and the dynamic of gelation. The model was compared with the experimental results and showed a satisfactory representation of the system after parameter adjusting. / No presente trabalho, o poli (ácido acrílico) super-absorvente foi sintetizado por polimerização em suspensão inversa, usando Span 60 como o dispersante, tolueno como fase orgânica, trimetilolpropano triacrilato como agente de reticulação e persulfato de sódio como iniciador. A síntese foi conduzida num reator de vidro em escala de bancada, operado em modo semi-batelada-batelada. As seguintes condições da reação foram avaliadas: os efeitos da concentração de iniciador, a temperatura, a porcentagem de agente de reticulação multifuncional e a concentração de monómero. Além disso, foram determinadas propriedades importantes, como a conversão e a fração de gel. Da mesma forma, foi desenvolvido um modelo de balanço populacional para simular o processo em conjunto com a técnica de fracionamento numérico, que é capaz de prever as propriedades pré-gel e pós-gel, o efeito do nível do agente de reticulação no polímero e as propriedades da dinâmica de gelificação. O modelo foi comparado com os resultados experimentais e mostrou uma representação satisfatória do sistema após o ajuste dos parâmetros.

Oxidation reactions are of prime importance at an industrial level and correspond to a huge market. Oxidation reactions are widely practiced in industry and are thoroughly studied in academic and industrial laboratories. Achievements in oxidation process resulted in the development of many new selective oxidation processes. Environmental protection also relies mainly on oxidation reactions. Remarkable results obtained in this field contributed to promote the social image of chemistry which gradually changes from being the enemy of nature to becoming its friend and savior. This study dealt with two aspects regarding oxidation process. The first aspect represented an experimental study for the partial oxidation of benzene to phenol using Pd membrane in the gaseous phase. The second part was a theoretical study for some of the advanced oxidation process (AOPs) which are applied for contaminant destructions in polluted waters. Niwa and coworkers reported a one step catalytic process to convert benzene to phenol using Pd membrane. According to their work, this technique will produce a higher yield than current cumene and nitrous oxide based industrial routes to phenol. A similar system to produce phenol from benzene in one step was studied in this work. Results at low conversion of benzene to phenol were obtained with a different selectivity from the reported work. High conversion to phenol was not obtained using the same arrangement as the reported one. High conversion to phenol was obtained using a scheme different from the one reported by Niwa et al1. It was found that producing phenol from benzene is not related to Pd-membrane since phenol was produced by passing all reactants over a Pd catalyst. Within the studied experimental conditions, formation of phenol was related to Pd catalyst since Pt catalyst was not capable of activating benzene to produce phenol. Other evidence was the result of a blank experiment, where no catalyst was used. From this experiment no phenol was produced. A kinetic model for the advanced oxidation process using ultraviolet light and hydrogen peroxide (UV/H2O2) in a completely mixed batch reactor has been tested for the destruction of humic acid in aqueous solutions. Known elementary chemical reactions with the corresponding rate constants were taken from the literature and used in this model. Photochemical reaction parameters of hydrogen peroxide and humic acid were also taken from the literature. Humic acid was assumed to be mainly destroyed by direct photolysis and radicals. The rate constant for the HA- reaction was optimized from range of values in the literature. Other fitted parameters were the rate constant of direct photolysis of hydrogen peroxide and humic acid. A series of reactions were proposed for formation of organic byproducts of humic acid destruction by direct photolysis and radicals. The corresponding rate constants were optimized based on the best fit within the range of available published data. This model doesn't assume the net formation of free radicals species is zero. The model was verified by predicting the degradation of HA and H2O2 for experimental data taken from the literature. The kinetic model predicted the effect of initial HA and H2O2 concentration on the process performance regarding the residual fraction of hydrogen peroxide and nonpurgeable dissolved organic carbon (NPDOC). The kinetic model was used to study the effect of the presence of carbonate/bicarbonate on the rate of degradation of NPDOC using hydrogen peroxide and UV (H2O2/UV) oxidation. Experimental data taken from literature were used to test the kinetic model in the presence of carbonate/bicarbonate at different concentrations. The kinetic model was able to describe the trend of the experimental data. The kinetic model simulations, along with the experimental data for the conditions in this work, showed a retardation effect on the rate of degradation of NPDOC due to the presence of bicarbonate and carbonate. This effect was attributed to the scavenging of the hydroxyl radicals by carbonate and bicarbonate. A kinetic model for the degradation of methyl tert-butyl ether (MTBE) in a batch reactor applying Fenton's reagent (FeII/ H2O2) and Fenton-like reagent (Feo/ H2O2) in aqueous solutions was proposed. All of the rate and equilibrium constants for hydrogen peroxide chemistry in aqueous solutions were taken from the literature. Rate and equilibrium constants for ferric and ferrous ions reactions in this model were taken from the reported values in the literature, except for the rate constant for the reaction of ferric ions with hydrogen peroxide where it was fitted within the range that was reported in the literature. Rate constant for iron dissolution was also a fitted parameter. The mechanism of MTBE degradation by the hydroxyl radicals was proposed based on literature studies. The kinetic model was tested on available experimental data from the literature which involved the use of Fenton's reagent and Fenton-like reagent for MTBE degradation. The degradation of MTBE in Fenton's reagent work was characterized to proceed by two stages, a fast one which involved the reaction of ferrous ions with hydrogen peroxide (FeII/H2O2 stage) and another, relatively, slower stage which involved the reaction of ferric ions with hydrogen peroxide (FeIII/H2O2 stage). The experimental data of MTBE degradation in the FeII/H2O2 stage were not sufficient to validate the model, however the model predictions of MTBE degradation in the FeIII/H2O2 stage was good. Also, the model was able to predict the byproducts formation from MTBE degradation and their degradation especially methyl acetate, and tert-butyl alcohol. The effect of each proposed reaction on MTBE degradation and the byproducts formation and degradation was elucidated based on a sensitivity analysis. The kinetic model predicted the degradation of MTBE for Fenton-like reagent for the tested experimental data. Matlab (R13) was used to solve the set of ordinary nonlinear stiff differential equations that described rate of species concentrations in each advanced oxidation kinetic model. Niwa, S. et al., Science 295 (2002) 105

Dans ce travail, l’effet du vieillissement thermique sur le comportement en fatigue ducomposite de poly (sulfure de phénylène) renforcé par fibres de verre (PPS/FV) a été étudié. Ce matériau est d’abord étudié par différentes méthodes d’analyse afin de déterminer ses caractéristiques physicochimiqueset mécaniques. Ensuite, le matériau subit un vieillissement thermo-oxydatif accéléré à différentes températures comprises entre 100 °C et 200 °C. Certaines caractéristiques du matériau sont d’ailleurs suivies au cours du vieillissement. A partir des résultats obtenus, un mécanisme d’oxydation estproposé et un modèle cinétique est développé. La validité de ce modèle est vérifiée par les résultats expérimentaux, essentiellement obtenus par la spectrométrie infrarouge. L’effet du vieillissement sur lecomportement mécanique est étudié par les deux axes suivants : D’abord d’une manière indirecte en étudiant l’évolution de la morphologie de la phase cristalline au cours du temps et ensuite par la méthode directe. Dans cette méthode directe, premièrement, le comportement en fatigue et en traction-traction duPPS/FV a été étudié en faisant varier la fréquence et l’amplitude de la sollicitation. La courbe de Wöhler est tracée en fonction du nombre de cycles à la rupture. Il a été constaté que le vieillissement modifie lepositionnement et l’allure de la courbe de Wöhler. Ensuite les éprouvettes vieillies à différentes températures sont testées en fatigue (traction-traction) avec une amplitude maximale (σmax=40 MPa) et un rapport de chargement (R=0,1) afin de suivre l’influence de la dégradation thermo-oxydative au cours du vieillissement. Il a été constaté que l’oxydation a un effet néfaste sur le comportement en fatigue du PPS/FV. Ce matériau perd significativement de ses performances même au début du vieillissement etsurtout à haute température de vieillissement. La perte de la performance en fatigue du matériau s’accentue au fur et à mesure que le processus d’oxydation se poursuit. / In this work, the effect of thermal aging on the fatigue behavior of a glass fiber reinforced poly (phenylene sulfide) composite (PPS/GF) was studied. This material is first characterized by differentmethods of analysis to determine its physicochemical and mechanical characteristics. Subsequently, thematerial undergoes accelerated thermo-oxidative aging at different temperatures between 100 °C and 200 °C. Some characteristics of this material are followed during thermal aging. From the results obtained, an oxidation mechanism is proposed and a kinetic model is developed. The validity of this model is verifiedby the experimental results, essentially obtained by infrared spectrometry. The effect of thermal aging on mechanical behavior is studied in two ways: Firstly, indirect manner by studying the evolution of the morphology of the crystalline phase over time and subsequently by the direct method. In this directmethod, firstly the tension-tension fatigue behavior of PPS/GF was studied by varying the frequency and amplitude of stress. The Wöhler curve is plotted on the basis of the number of cycles at break. Thermalaging has been found to alter the position and shape of the Wöhler curve. Then the samples aged at different temperatures were tested by tension-tension fatigue with a maximum amplitude (σmax = 40 MPa)and a loading ratio (R = 0.1) to follow the influence of thermo-oxidative degradation during aging. It has been found that thermal aging has a detrimental effect on the fatigue behavior of PPS/GF. This material loses its performance significantly even at the beginning of aging, especially in high aging temperature.The loss of fatigue performance grows in the oven as the oxidation process continues.

La thèse présentée traite principalement de l'influence de la composition et de l’état de surface d’électrodes à base de Ni sur la cinétique et le mécanisme des réactions d'oxydation/dégagement de l'hydrogène (HOR/HER) en milieu alcalin. En combinant les résultats de mesures électrochimiques avec une modélisation microcinétique, il a pu être montré que l'activité spécifique du Ni pour l’HOR/HER augmente jusqu'à 10 fois en présence à la fois d’oxydes de Ni et de Ni métallique à la surface de l'électrode. En outre, l'influence de l'addition d’un second métal aux électrocatalyseurs à base Ni sur leurs activités pour l’HOR/HER a été étudiée dans le cas des systèmes NiMo/C et NiCu/C. Dans les deux cas, une augmentation de l'activité spécifique a été observée par rapport à l'échantillon Ni/C de référence et a été attribuée à une diminution de l'énergie d'adsorption de l'hydrogène adsorbé sur Ni, espèce intermédiaire de l’HOR/HER. / The present thesis is mainly focused on the influence of the surface state of Ni electrodes on the kinetics and the mechanism of the hydrogen oxidation/evolution reactions (HOR/HER) in alkaline medium. By combining the results of electrochemical measurements with microkinetic modeling, it was shown that specific activity of Ni in the HOR/HER increases up to 10 times if along with metallic Ni, Ni oxide species are present on the electrode surface. In addition, the effect of the addition of a second metal to Ni electrocatalysts on their activity in the HOR/HER was investigated for NiMo/C and NiCu/C systems. In both cases an enhancement of specific activity was observed in comparison with the reference Ni/C sample, which was assigned to a decrease of the adsorption energy of the hydrogen intermediate on Ni participating in the HOR/HER.

<p>U ovom radu pripremljeni su različiti polimerni i keramički nanostrukturni materijali, u cilju ispitivanja uticaja vrste i udela nanopunila (čađ, fuleren, silicijum(IV)oksid, aluminijum(III)oksid i titanijum(IV)oksid) na strukturu, reolo&scaron;ko i toplotno pona&scaron;anje kompozita, dobijenih na osnovu stirena, metilmetakrilata i akrilamida, primenom različitih metoda sinteze. Ispitivan je uticaj prisustva različitog udela nanočestica (1, 3 i 5 %<em> m/m</em>) na kinetiku polimerizacije stirena, i na oblast prelaska u staklasto stanje polistirenskih hibridnih materijala. Sintetisana je i serija nanokompozita polimerizacijom metilmetakrilata u prisustvu čestica (silicijum(IV)oksid, aluminijum (III)oksid i titanijum(IV)oksid) različitih dimenzija i hidrofilnosti, ali istog zapreminskog udela (1 %<em> v/v</em>). Na osnovu primene izotermne diferencijalno skanirajude metode (DSC), razvijen je kinetički model za opisivanje dve razičite reakcije tokom polimerizacije vinilnih monomera (reakciju prvog reda i samoubrzanje), i izračunata je debljina međufaznog sloja polimera na čestici u cilju određivanja njegovog uticaja na temperaturu prelaska u staklasto stanje hibridnih materijala. Za ispitivanje strukture i morfologije polistiren/silicijum(IV)oksid nanokompozita dobijenih metodom isparavanja rastvarača, kori&scaron;dene su infracrvena spektroskopija sa Furijeovom transformacijom (FT-IR) i skanirajuda elektronska mikroskopija (SEM). Radi utvrđivanja uticaja udela hidrofobnog silicijum(IV)oksida (2, 5, 10, 15 i 30 %<em> m/m</em>) na toplotnu postojanost polistirenskih materijala, primenjene su istovremena termogravimetrijska i diferencijalno skanirajuda analiza (TG-DSC). Takođe, određen je uticaj veličine čestice fulerena C60 i submikronske čestice čađi na reolo&scaron;ka svojstva polistirenskih kompozita sintetisanih taloženjem polimera iz rastvora. Ispitivanjem reolo&scaron;kog pona&scaron;anja hibridnih materijala, proučavan je uticaj veličine čestica, molekulske mase polimera i indeksa polidisperznosti na viskoznost polistirenskih kompozita. Na osnovu<em> in-situ</em> reolo&scaron;kih analiza polimerizacije u toku želiranja suspenzije nanočestica aluminijum(III)oksida u vodenom rastvoru monomera metakrilamida i N,N&rsquo;-metilenbisakrilamida, utvrđena je jaka katalitička aktivnost povr&scaron;ine aluminijum(III)oksida na nastajanje slobodnih radikala. Radi nalaženja veze između željenih svojstava keramičkih proizvoda i načina njihovog dobijanja, proučavan je uticaj uslova vođenja polimerizacije na slaganje čestica u dobijenom odlivku i na gustinu krajnjeg sinterovanog proizvoda.</p> / <p>In this work, polymeric and ceramic nanostructured materials were prepared using different methods, in order to investigate the influence of nanofiller content and its type (carbon black, fullerene, silica, alumina and titania) on the structure, rheological and thermal behavior of composites, based on styrene, methylmethacrylate and acrylamide. The effect of particles content (1, 3 and 5 wt. %) on the kinetics of styrene radical polymerization and on the glass transition temperature of polystyrene/silica composites was investigated. A series of polymethylmethacrylate nanocomposites containing 1 vol. % of silica, alumina or titania particles (differing in dimensions and surface properties) was obtained. On the basis of isothermal differential scanning calorimetry (DSC), the kinetic model for describing two reactions during vinyl monomer polymerization (first order and autoacceleration) was developed, and the thickness of interfacial layer formed on nanoparticle surface was determined, in order to investigate its influence on the glass transition temperature of polymethylmethacrylate hybrid materials. The structure and the morphology of polystyrene/silica nanocomposites prepared by solvent evaporation were investigated using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The influence of&nbsp; hydrophobic silica content (2, 5, 10, 15 and 30 wt. %) on polystyrene thermal stability was studied by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). The effect of fullerene C60 and submicron carbon black particle size on rheological properties of polystyrene composites prepared by the rapid coprecipitation was determined. Following the rheology of hybrid melts, the influence of filler size, molecular weight and polydispersity of polymer matrix on the viscosity of polystyrene composites was studied. On the basis of in-situ rheology analysis of polymerization process during the gelation of alumina nanoparticles suspension in aqueous solution of methacrylamide and N,N&rsquo;- methylene bisacrylamide monomers, the strong catalytic activity of alumina surface on the free radicals formation was determined. In order to find the correlation between desired properties of ceramic products and their preparation procedure route, the influence of polymerization conditions on the green body structure and sintered body density was studied in details.</p>

Ce travail de thèse aborde l’étude mécanistique de systèmes photoamorceurs complexes et la modélisation cinétique du processus de photopolymérisation. Dans un premier temps, le mécanisme photochimique d’un système combinant le [Ru(bpy)3]2+ et des agents RAFT pour l’amorçage et le contrôle d’un processus radicalaire a été étudié. Un transfert d’énergie a été clairement démontré, contredisant le mécanisme de transfert d’électron généralement proposé. Un système photoamorceur à 3 composants bicyclique dual ITX/IOD+/RSH a ensuite été considéré pour la synthèse de matériaux hybrides organiques-inorganiques. Sous excitation lumineuse, ce système produit simultanément des radicaux et des protons, permettant d’amorcer, respectivement, des processus de polymérisation radicalaire et sol-gel. Dans un second temps, l’interdépendance entre les cinétiques de photopolymérisation et l’évolution des propriétés du milieu réactionnel a été étudiée par le biais du développement d’un modèle cinétique permettant la simulation de l’intégralité du processus de photopolymérisation. Des systèmes photoamorceurs de complexité croissante ont été inclus afin d’étudier les spécificités de leurs cinétiques. Un système de type I a permis de mettre en évidence les modes de terminaison majoritaires et leur évolution au cours de la synthèse des polymères, tandis que le rôle non négligeable du transfert d’électron inverse a été mis en exergue pour des systèmes photoamorceurs de type II. La fonction d’agent de terminaison d’un photoproduit issu d’un colorant cationique, ainsi que certaines spécificités des systèmes photocycliques à 3 composants, ont été finalement étudiés grâce à la modélisation. / This thesis deals with the mechanistic study of complex photoinitiating systems and the kinetic modeling of the photopolymerization process. In a first time, the photochemical mechanism of a system combining [Ru(bpy)3]2+ and RAFT agents for the initiation and control of a radical process has been studied. An energy transfer has been clearly demonstrated, contradicting the electron transfer mechanism generally proposed. A dual bicyclic three-component photoinitiating system ITX/IOD+/RSH has been considered for the synthesis of organic-inorganic hybrid materials. Under light exposure, this system produces simultaneously radicals and protons, enabling the initiation of a radical polymerization and a sol-gel process, respectively. In a second time, interdependence between photopolymerization kinetics and evolution of the medium’s properties has been studied, through developing a kinetic model for the simulation of the whole photopolymerization process. Photoinitiating systems of growing complexity have been included in order to study specificities of their kinetics. A type-I system has shown major termination modes and their evolution during the polymer synthesis, while the non-negligible role of back electron transfer has been highlighted for type-II photoinitiating systems. Role of terminating agent of a photoproduct based on a cationic dye, as well as some specificities of photocyclic three-component systems, have been finally studied with the model.